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Hi,
I have been having issues with large amounts of parasitic cantilever motions. Even when I use the autoconfig button on the force curve monitor nothing seems to change. Why would the autoconfig not remove the parasitic motions? Could this be indicative of using the wrong probe? I have tried altering the PF set-point over a range of 30mV - .3V with no change in parasitic motions. Any suggestions?
I use a dimension ICON system and I am scanning thin polymer coatings on metal substrates.
Thanks!
Lauren,This may also be a laser interference effect. The samples that you are running (polymer coating on metal substrate) sound like they may be highly reflective. Try to minimize the interference through better laser alignment (maximize the sum). Also try OLTESPA, or if you can tolerate higher force OTESP (they both are a little wider).You can also, after engage, try to manually input a small lift height. This parameter is in the PFT control scan list; it is essentially a manual auto configure. Try down to 10-20nm, but back off if your force curves start to look bad.Best,Steve
Hi Lauren,
I am not sure what eactly you refer to when you mention "parasitic cantilever motions". If you refer to the oscillations that occur after the tip leaves the surface that is a motion that is not really going to be removed. This motion is due to the energy stored being released. The oscillation will be stronger the more adhesive your sample is and the softer your lever. Nothing to worry about so much as the point of maximum adhesion is being used and the oscillations afterwards are being ignored (but displayed). Slow frequency oscillations on the approach on the other hand can be caused by laser interference. Even though the routing will remove some if you have a lot of it it is advisable to align to minimize that effect.
Stefan
Hi Stefan,
Thanks for your reply. I was referring to the slow frequency oscillations you mention. My force curves appear like the "before autoconfig" image in the PF-QNM Users Manual section 2.8. It is a large bowing type motion that is persistent in both the approach and the withdraw (mine is much larger than that seen in the manual). My laser is also aligned square in the center of the target for the detector. The motions in the force curve are lessened (but still there) when I scan 500 nm as opposed to 2 um, if this means anything...
Thanks again for the suggestions!
Lauren
Hi Steve,
Yes, they are very reflective. I will try these suggestions- thanks!!
Aligning the detector so that the beam is centered is good but will not eliminate laser interference. You have to optimize the point where the laser hits the cantilever in order to achieve that. The interference is caused by light spilling over the lever and being reflected off the sample.
Stefan and Steve,
What a simple fix! It was the laser interference. I really have to move that beam back off the point of the probe, but it eliminates the effect. You made my day- thanks again!